Disease: Canary malaria.
Hosts: This species was first found in the English sparrow. It is common in passerine birds and has also been found in canaries.
Location: Erythrocytes. The exo-erythrocytic stages are in endothelial cells.
Morphology: The gametocytes and schizonts are more or less round, displacing and often expelling the host cell nucleus. The pigment granules in the gametocytes are coarse, often elongate and rod-like. The schizonts produce 6 to 24 merozoites.
Life Cycle: The life cycle of this species has been studied extensively (Bray, 1957). It is similar to that of other avian species of Plasmodium. Exoerythrocytic stages occur in the endothelial cells. The asexual cycle takes 24 hours, and synchronicity is high. Huff (1954) listed 8 species of Culex, 3 each of Aedes and Anopheles and 1 of Psorophora which can act as vectors. However, he remarked that only 46% of the mosquito species which had been tested were susceptible.
Pathogenesis: P. cathemerium causes a highly fatal disease in canaries. Herman and Vail (1942) reported it in a canary in California, and Mathey (1955a) described an outbreak in a canary breeding establishment in that state in which possibly 165 out of 700 birds died.
Affected canaries have subcutaneous hemorrhages, anemia, splenomegaly and hepatomegaly. Mathey (1955a) described swelling in the region of the eyes. Hewitt (1939) found splenic infarcts in 47% of his experimentally infected canaries.